APA-referens (7:e uppl.)
Duvall, F. P. (1983). The Structure and ontogeny of corvine social play of the rook (Corvus frugilegus, L.) and the hooded crow (Corvus corone cornix, L.). Freie Univ., Fachbereich Biologie.
Chicago-referens (17:e uppl.)
Duvall, Fern Park. The Structure and Ontogeny of Corvine Social Play of the Rook (Corvus Frugilegus, L.) and the Hooded Crow (Corvus Corone Cornix, L.). Berlin: Freie Univ., Fachbereich Biologie, 1983.
MLA-referens (9:e uppl.)
Duvall, Fern Park. The Structure and Ontogeny of Corvine Social Play of the Rook (Corvus Frugilegus, L.) and the Hooded Crow (Corvus Corone Cornix, L.). Freie Univ., Fachbereich Biologie, 1983.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.